From 5bc8028696ae8d5aa2c60db87aea3d00f9d7aebd Mon Sep 17 00:00:00 2001
From: Jasper Van der Jeugt <jaspervdj@gmail.com>
Date: Sun, 26 Dec 2010 00:09:35 +0100
Subject: Add DirectedGraph to DOT module

---
 src/Hakyll/Core/DirectedGraph/Dot.hs | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 src/Hakyll/Core/DirectedGraph/Dot.hs

(limited to 'src/Hakyll')

diff --git a/src/Hakyll/Core/DirectedGraph/Dot.hs b/src/Hakyll/Core/DirectedGraph/Dot.hs
new file mode 100644
index 0000000..8289992
--- /dev/null
+++ b/src/Hakyll/Core/DirectedGraph/Dot.hs
@@ -0,0 +1,30 @@
+-- | Dump a directed graph in dot format. Used for debugging purposes
+--
+module Hakyll.Core.DirectedGraph.Dot
+    ( toDot
+    , writeDot
+    ) where
+
+import Hakyll.Core.DirectedGraph
+import qualified Data.Set as S
+
+-- | Convert a directed graph into dot format for debugging purposes
+--
+toDot :: Ord a
+      => (a -> String)    -- ^ Convert nodes to dot names
+      -> DirectedGraph a  -- ^ Graph to dump
+      -> String           -- ^ Resulting string
+toDot showTag graph = unlines $ concat
+    [ return "digraph dependencies {"
+    , concatMap showNode (S.toList $ nodes graph)
+    , return "}"
+    ]
+  where
+    showNode node = map (showEdge node) $ S.toList $ neighbours node graph
+    showEdge x y = "    \"" ++ showTag x ++ "\" -> \"" ++ showTag y ++ "\";"
+
+-- | Write out the @.dot@ file to a given file path. See 'toDot' for more
+-- information.
+--
+writeDot :: Ord a => FilePath -> (a -> String) -> DirectedGraph a -> IO ()
+writeDot path showTag = writeFile path . toDot showTag
-- 
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